Bioremoval of Tl (I) by PVA-immobilized sulfate-reducing bacteria

As scattered elements, thallium (Tl) contamination poses a significant threat to human health due its high toxicity. Sulfate-reducing bacteria (SRB) embedded in PVA-sodium alginate matrix was utilized as a novel bio-remover to remove Tl from aqueous solution. The effect of pH, temperature, and initial Tl concentration on removal capacity of immobilized beads were studied and discussed in this work. The optimum bio-removal conditions were at pH value of 6, temperature of 35ºC, and initial Tl concentration of 50 mg.L⁻¹. The pseudo second-order model for Tl adsorption was applicable to all the removal data over the entire time range and intralayer diffusion was not the only rate-determining step. The bio-removal data conformed well to Langmuir isotherm model. Fourier transform infrared spectroscopy showed that sulfate reduction played an important role in Tl removal. The groups of carboxylate radical might be involved in sulfate reduction reaction.